This invention relates to electronic circuitry for voltage regulation and, more particularly, to switching voltage regulators responsive to varying direct current input voltages to provide a regulated output voltage with minimal power dissipation.
In certain direct current circuit applications, there is required a low level control voltage referenced to, or of the same polarity as, the positive source voltage. One such application is in static power switching apparatus. By referencing the control voltage to the positive side of the supply, current may be sensed by a shunt resistor in series with a main power switch between source and load in DC power controllers without large common mode voltage problems. Numerous series voltage regulators are known that can accomplish the basic required function, but they are characterized by relatively high power loss and heat dissipation whih makes them undesirable where such considerations are important. Additionally, applications of such circuits encounter overdrive requirements to permit operability over a wide range of input voltages such as at least an order of magnitude. For example, an application of interest is in power controllers where the input voltage may vary over a range of from about 20 to 300 volts DC and the known circuitry of the prior art is generally efficient in performance over such a wide range.
Switching voltage regulators are generally known circuits that maintain a regulated output voltage level by transistor means that switches at the high voltage levels and encounters high losses over an extended range of input voltage, as such circuits have been heretofore arranged.